Fluorogenic
probes used for SMF imaging of nanoscale catalysts.
(a) Reductive N-deoxygenation of resazurin produces fluorescent resorufin.
(b) The reduction of the para-nitro group of 8-(3,4-dinitrophenyl)-1,3,5,7-tetramethyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (DN-BODIPY) into a hydroxylamino group produces
the fluorescent HN-BODIPY. (c) Oxidative N-deacetylation of Amplex
red produces resorufin. (d) Oxidative cleavage of the aminophenyl
group of 3′-(p-aminophenyl) fluorescein (APF)
produces fluorescein. Both Amplex red and APF can either be directly
oxidized by the catalyst to produce the fluorescent product, or they
can be activated by reactive oxygen species generated at the catalyst
surface. (e) The acid-catalyzed condensation of furfuryl alcohol produces
fluorescent oligomers. All probes except the one shown in panel (b)
are commercially available. The synthesis of the DN-BODIPY probe is
described in ref (187).